Abstract
In this paper a methodology to analyze Bike Sharing system efficiency is proposed focusing on the service availability at bike stations. The fundamental requirements and the main features of the system are outlined. In order to describe the state of the system, a synthetic indicator has been defined and its value derives from the solution of an optimization problem that minimizes the total amount of the distance travelled by bike transferring vehicles among stations. The proposed method is applied to a test casecreated by selecting a set of stations of the system operating in Barcelona.